U.S. patent application number 09/740864 was filed with the patent office on 2002-05-02 for sample ejection device.
Invention is credited to Busch, Michael, Moller, Dirk, Sollbohmer, Olaf.
Application Number | 20020051737 09/740864 |
Document ID | / |
Family ID | 7948327 |
Filed Date | 2002-05-02 |
United States Patent
Application |
20020051737 |
Kind Code |
A1 |
Sollbohmer, Olaf ; et
al. |
May 2, 2002 |
Sample ejection device
Abstract
A sample ejection device for pipetting or dispensing very small
quantities comprises a sample ejection head (10). The sample
ejection head (10) is provided with a plurality of pipettes (12), a
plurality of micropumps (46) for conveying very small quantities,
and at least one storage container (24) connected with the pipettes
(12). The sample ejection device further comprises a control unit
(26) for controlling the sample ejection head (10) and a monitoring
unit (28) for monitoring the sample ejection head (10). For
facilitating exchange of storage containers (24) or pipettes (12)
the sample ejection head (10) is exchangeable as a whole. It is
thus not necessary to exchange individual storage containers (24)
or individual pipettes (12) during a pipetting process. Exchange of
the entire sample ejection head (10) can thus be effected
considerably more quickly.
Inventors: |
Sollbohmer, Olaf; (Hamburg,
DE) ; Moller, Dirk; (Hamburg, DE) ; Busch,
Michael; (Hamburg, DE) |
Correspondence
Address: |
DILLER, RAMIK & WIGHT, P.C.
Merrion Square
Suite 101
7345 McWhorter Place
Annandale
VA
22003
US
|
Family ID: |
7948327 |
Appl. No.: |
09/740864 |
Filed: |
December 21, 2000 |
Current U.S.
Class: |
422/400 ; 422/63;
422/67 |
Current CPC
Class: |
B01J 2219/00315
20130101; B01J 2219/00691 20130101; B01J 2219/00364 20130101; B01J
2219/00527 20130101; G01N 35/1065 20130101; G01N 2035/00425
20130101; B01J 2219/00351 20130101; B01J 2219/00689 20130101; B01J
2219/00659 20130101; G01N 2035/1025 20130101; C40B 60/14 20130101;
G01N 35/1004 20130101 |
Class at
Publication: |
422/100 ; 422/63;
422/67 |
International
Class: |
B01L 003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 1, 2000 |
DE |
200 18 628.0 |
Claims
What is claimed is:
1. Sample ejection device for pipetting and/or dispensing very
small quantities of biological and/or chemical substances, the
device comprising: at least one pipetting and/or dispensing means
(12), at least one storage container (24) connected with the
pipetting and/or dispensing means (12), at least one means (46) for
conveying very small quantities, and a control unit (26), wherein a
sample ejection head (10) is provided which comprises the pipetting
and/or dispensing means (12), the means (46) for conveying very
small quantities, and the storage container (24) as well as a
holder (32) which is, together with the parts (12,24,46) attached
thereto, exchangeably fastened to a reception part (22).
2. Sample ejection device according to claim 1, wherein the holder
(32) comprises a plurality of attachment bolts or pipetting
openings for fastening purposes and the reception part (22)
comprises a plurality of pipetting openings or attachment bolts
respectively.
3. Sample ejection device according to claim 1, wherein the holder
(32) comprises a groove (50) or a projection for fastening purposes
and the reception part (22) comprises a projection or a groove (52)
respectively.
4. Sample ejection device according to claim 3, wherein the
projection and the groove (50) are of dovetail configuration.
5. Sample ejection head comprising at least one pipetting and/or
dispensing means (12), at least one means (46) for conveying very
small quantities, and at least one storage container (24) connected
with the pipetting and/or dispensing means (12), wherein a common
holder (32) supporting the pipetting and/or dispensing means (12),
the means (46) for conveying very small quantities and the storage
container (24) is provided, the holder (32), together with the
parts (12,24,46) attached thereto, being exchangeable as a
whole.
6. Sample ejection head according to claim 5, wherein the holder
(32) comprises a plurality of attachment bolts or pipetting
openings for fastening purposes.
7. Sample ejection head according to claim 5, wherein the holder
(32) comprises a groove (50) or a projection for fastening
purposes.
8. Sample ejection head according to claim 7, wherein the
projection and the groove (50) are of dovetail configuration.
9. Sample ejection device according to claim 1 or sample ejection
head according to claim 5, wherein the sample ejection head (10)
and/or the reception part (22) comprise an adjusting means.
10. Sample ejection device according to claim 1 or sample ejection
head according to claim 5, wherein the sample ejection head (10)
comprises a cooling and/or heating unit connected with the storage
container (24).
11. Sample ejection device according to claim 1 or sample ejection
head according to claim 5, wherein the sample ejection head (10)
comprises at least one controller (48) connected with the means
(46) for conveying very small quantities.
12. Sample ejection device according to claim 1 or sample ejection
head according to claim 5, wherein the sample ejection head (10)
comprises a cleaning fluid reservoir connected with the at least
one pipetting and/or dispensing means (12).
13. Sample ejection device according to claim 1 or sample ejection
head according to claim 5, wherein the storage container (24) is
exchangeable.
14. Sample ejection device according to claim 1 or sample ejection
head according to claim 5, wherein a level sensor is associated
with the storage container (24).
15. Sample ejection device according to claim 1 or sample ejection
head according to claim 5, wherein the sample ejection device
comprises a cooling and/or heating unit and the temperature of the
storage container (24) is controlled via the holder (32).
16. Sample ejection device according to claim 1 or sample ejection
head according to claim 5, wherein at least two, preferably four,
more preferably eight and in particular sixteen pipetting and/or
dispensing means (12) are arranged on a sample ejection head
(10).
17. Sample ejection device according to claim 1 or sample ejection
head according to claim 5, wherein the very small quantities are
smaller than 500 nl, preferably smaller than 50 nl, more preferably
smaller than 5 nl and lie in particular in the subnanoliter
range.
18. Sample ejection device according to claim 1 or sample ejection
head according to claim 5, wherein the means (46) for conveying
very small quantities forms part of the pipetting and/or dispensing
means (12).
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a sample ejection device
for pipetting and/or dispensing very small quantities of biological
and/or chemical substances and to a sample ejection head provided
on the sample ejection device.
[0002] Such ejection devices are for example employed for
high-throughput screening in the fields of diagnostics and research
in the field of pharmazeutical products. In the case of
high-throughput screening titer plates comprising for example 1536
or 2080 wells are filled with sample fluids and subsequently
examined with the aid of an optical measuring instrument. The very
small quantities contained in the wells are normally smaller than
500 nl, in particular smaller than 50 nl, more preferably smaller
than 5 nl. In particular quantities in the subnanoliter range are
filled into the wells. For filling the wells the sample ejection
device comprises at least one pipetting and/or dispensing means,
for example pipettes or dispensers. For dispensing and, if
necessary, taking up of fluids the pipetting and/or dispensing
means is connected with a means for conveying very small
quantities, for example a micropump. Such micropumps normally
comprise piezoelectric elements such that droplets in a volume of a
few nanoliters or subnanoliters may be produced by applying a
voltage.
[0003] The pipetting and/or dispensing means is further connected
with a storage container containing a test fluid or a system fluid.
Sample ejection devices are normally provided with a control unit
and, if necessary, a monitoring unit which control and monitor the
pipetting and/or dispensing means and the means for conveying very
small quantities. Further said units control and monitor for
example a stage on which one or a plurality of carrier plate/plates
having an array of sample wells and a cleaning station are located.
In particular when very small quantities are dispensed by the
pipettes or dispensers, the position of the pipettes or dispensers
relative to the carrier plate is controlled and monitored.
[0004] During a conventional pipetting process sample fluids are
aspirated from the wells of a first carrier plate into the
pipettes. The pipettes have a passage therethrough, said passage
having a volume and a dispensing end and a system end, said
dispensing end having a passage tip opening. For intake of the
sample fluids the pipettes are filled with a system fluid with the
sample fluid being aspirated through its dispensing end into the
pipette by applying a vacuum. After the intake process a sample or
test fluid is thus located in and proximate to the dispensing end
of the pipette and followed by a system fluid, the latter being
located in and proximate to the system end. The use of a system
fluid to fill parts of the pipettes is particularly advantageous
since the test fluids are in most cases extremely expensive.
Subsequently, the stage is moved such that the pipettes are
arranged above the wells of a second carrier plate. The pipettes
are moved in vertical direction and feed, in several steps, the
sample fluids taken from the first carrier plate in very small
quantities to the wells of the second carrier plate. For this
purpose the pipettes are connected for example with micropumps
which dispense very small quantities of aspirated test fluid to a
plurality of wells.
[0005] In the next step the pipettes are cleaned. For this purpose
the stage is moved such that the pipettes are arranged above a
cleaning station. During the cleaning process a cleaning fluid
flows through the pipettes. The system fluid may be used as
cleaning fluid and may be contained in the storage container
connected with the pipettes. For removal of cleaning fluid residues
from the passage tip opening, the pipettes are dabbed on an
absorptive fleece. The pipettes are also cleaned from outside.
[0006] Then the stage is moved such that the pipettes are arranged
again above the corresponding wells of the first carrier plate.
[0007] Instead of the movements being carried out by a stage, all
movements may be executed by the pipettes. However, normally a
stage or any other suitable transport means is used for moving the
carrier plates in a horizontal plane while the movement in vertical
direction is carried out by the pipettes or dispensers.
[0008] Exchanging the system fluid requires removal of the tubes
arranged between the storage container containing the system fluid
and the individual pipettes to allow the storage container to be
exchanged. The exchange of the storage container is thus
time-consuming and cost-intensive. Further, during removal of the
tubes from the pipettes or the storage container system fluid
frequently gets in contact with the device. This may result in
contamination of the carrier plates and thus in falsification of
measuring results. Removal of the tubes is further disadvantageous
in that impurities may enter the pipettes. This may lead to
clogging of the extremely thin pipettes.
[0009] Further the pipettes must be frequently exchanged, for
example as a function of the viscosity of the test fluid used.
Moreover, an exchange of the pipettes as a function of the quantity
to be pipetted is necessary. When the pipettes are exchanged, the
connecting tubes must be removed from the pipettes so that
contamination may occur. Further the exchange of pipettes is
particulary time-consuming and expensive since each pipette must be
indivdually adjusted. Adjustment of the pipettes is extremely
difficult due to the small distances between the wells into which
the pipettes dispense their test fluids.
[0010] If the pipetting and/or dispensing means is at least one
dispenser, a test fluid is fed via the dispenser to the wells. The
dispensers have a passage therethrough, said passage having a
volume and a dispensing end and a system end, said dispensing end
having a passage tip opening. In contrast to the pipettes which
aspirate test fluid through the passage tip opening, the passage of
the dispenser is filled with test fluid via the system end. For
this purpose a test fluid is contained in the storage container
which is connected with the dispenser at the system end. The
dispenser may be provided with a micropump which feeds very small
quantities of test fluid to the wells. When the storage container
or the dispensers are exchanged, the problems described above may
occur.
[0011] It is an object of the present invention to provide a sample
ejection device which allows the storage container and/or the
pipetting and/or dispensing means to be exchanged in a more rapid
and simple way wherein in particular the danger of contamination is
avoided.
SUMMARY OF THE INVENTION
[0012] The sample ejection device according to the invention
comprises a sample ejection head which can be exchanged as a whole.
The sample ejection head comprises, according to the invention, at
least one pipetting and/or dispensing means, at least a means for
conveying very small quantities, and at least one storage container
connected with the pipetting and/or dispensing means. These and
possibly further parts of the sample ejection head are supported on
a common holder. Said holder is exchangeably connected with a
reception part of the sample ejection device. According to the
invention the sample ejection head is thus always exchanged as a
whole.
[0013] The pipetting and/or dispensing means is in particular one
pipette or a plurality of pipettes or one dispenser or a plurality
of dispensers. They are preferably connected with a micropump used
as a means for conveying very small quantities. Preferably each
individual pipette or each individual dispenser is connected with a
micropump which forms a unit with the pipette or the dispenser.
[0014] Exchange of individual pipettes/dispensers or individual
storage containers is not required in the sample ejection device
according to the invention. If for example a new test fluid is to
be filled in during a screening process, it is merely necessary to
replace the entire sample ejection head by another sample ejection
head which comprises for example a storage container containg the
corresponding test fluid or other pipettes/dispensers. The sample
ejection head to be replaced may thus be prepared while the
dispensing or pipetting process is carried out with another sample
ejection head. Exchange of pipettes/dispensers, removal of tubes
and cleaning of the sample ejection head can thus be performed
outside the sample ejection device. This offers the advantage that
the sample ejection device is not contaminated by leaking system
and/or test fluid. Clogging of the pipettes/dispensers is also
avoided. Further the pipetting process is interrupted for a
considerably shorter period when the sample ejection head is
exchanged as a whole instead of exchange of individual components
of the sample ejection head since exchange of a storage container
and removing and attaching of tubes are not necessary.
[0015] Preferably the holder of the sample ejection head comprises
a quick-acting closure. Said closure is for example an eccentric
connected with a lever with the holder being pressed against the
reception part and retained there. Further a clamping closure may
for example be provided as quick-acting closure where a clamp
connected with a lever is shifted for fastening or releasing the
holder.
[0016] For fastening purposes the holder preferably comprises a
groove or a projection interacting with a projection or groove
provided on the reception part. Preferably the groove and the
projection are of dovetail configuration. In this embodiment the
sample ejection head can be attached along dovetailed guide rails
to the reception part connected with the sample ejection device.
Said guide rails can precisely define the position of the sample
ejection head. In addition to the guide rails a quick-acting
closure may be provided.
[0017] For precise definition of the position of the sample
ejection head on the sample ejection device it is further possible
to provide the holder with a plurality of attachment bolts or
pipetting openings which interact with pipetting openings and
attachment bolts respectively on the reception part. Preferably
three bolts and three corresponding pipetting openings are
provided. The bolts can be configured relatively to the openings
such that at least one bolt together with the corresponding opening
defines the horizontal position and another bolt defines the
vertical position. The position of the sample ejection head
relative to the the reception part of the sample ejection device is
thus defined in a simple manner.
[0018] The present invention further relates to a sample ejection
head comprising, as described above, at least one pipetting and/or
dispensing means, at least one means for conveying very small
quantities, and at least one storage container connected with the
pipetting and/or dispensing means. The sample ejection head
according to the invention is configured such that it comprises a
common holder supporting in particular the pipettes/dispensers,
micropumps and the storage container. The sample ejection head thus
forms a unit which is exchangeable as a whole. For fastening
purposes the sample ejection head may comprise, as described above,
a quick-acting closure, a groove, a projection, attachment bolts or
pipetting openings. The groove or projections are preferably of
dovetail configuration.
[0019] In a preferred embodiment the sample ejection head and/or
the reception part provided on the sample ejection device comprises
an adjusting device. Said adjusting device serves for precise
definition of the position of the sample ejection head. Since the
position of the individual pipettes/dispensers in the sample
ejection head is defined and remains unchanged when the sample
ejection head is exchanged, adjustment of the sample ejection head
as a whole is sufficient. Adjustment of the individual
pipettes/dispensers can be omitted or serves only for fine
adjustment. In this connection it is particularly advantageous that
in the event of exchange of the entire sample ejection head no
tubes must be removed from the individual pipettes/dispensers since
the forces exerted during removal of tubes frequently lead to
maladjustment of the pipettes/dispensers.
[0020] The storage container, which forms part of the sample
ejection head, may be connected with a cooling and/or heating unit
by means of which the test fluid may be kept for example at the
temperature required for preserving the fluid.
[0021] The cooling and/or heating unit preferably also forms part
of the sample ejection head.
[0022] In particular when the sample ejection head comprises a
plurality of storage containers which must be kept at different
temperatures, it is advantageous to provide the cooling and/or
heating unit on the sample ejection head.
[0023] It is also possible to manufacture the holder of the sample
ejection head from a heat-conducting material such that a cooling
and/or heating unit can be provided in the sample ejection device.
Cooling and/or heating of fluids contained in one storage container
or a plurality of storage containers is then effected via the
heat-conducting holder. For this purpose the storage containers are
heat-conductingly connected with the holder. This embodiment is
less expensive than provision of a cooling and/or heating unit on
the sample ejection head. However, when the cooling and/or heating
unit is provided in the sample ejection device it is not possible
or extremely difficult to keep fluids contained in a plurality of
storage containers at different temperatures. It would for exampe
be feasible to insulate cooling units or storage containers and
keep another storage container at a higher temperature via the
holder.
[0024] Further the sample ejection head preferably comprises at
least one controller connected with the micropumps for controlling
said micropumps. In this embodiment, the controller, too, is
exchanged when the sample ejection head is replaced as a whole.
Electrical connections between the micropumps and the controller
need therefore not be disconnected when the pipettes/dispensers are
exchanged.
[0025] Further the sample ejection head may comprise a control box
connected with the individual micropumps. The control box is
provided with a unique plug for connecting the control box with a
controller arranged in the sample ejection device. Thus removal of
the sample ejection head only requires a unique plug to be
unplugged from a control box. It is not necessary to disconnect
individual electrical connections each leading to an individual
micropump. Unplugging of a plug from a control box further offers
the advantage that maladjustment of pipettes/dispensers is
prevented since it is not necessary to unplug individual plugs from
the micropumps directly arranged on the pipettes/dispensers.
Preferably the control box controls four, in particular eight, and
more preferably sixteen micropumps.
[0026] During pipetting of fluids it is further necessary to
control the pressure of the system fluid by means of a pressure
controller. For this purpose a corresponding pressure controller
may for example be provided directly on the sample ejection head.
As the system fluid is preferably also used for cleaning the
pipettes, a storage container containing system fluid is preferably
provided in the sample ejection device since at this location it is
easier to arrange containers adapted to accommodate larger fluid
quantities. For connecting said system fluid container in the
sample ejection device with the pipettes a unique fluid coupling is
provided on the sample ejection head. From the fluid coupling the
system fluid is then fed via a plurality of tubes to the individual
pipettes. For controlling individual pipettes a suitable circuit
controlling the system fluid pressure can be provided in individual
pipettes. In this embodiment merely a single fluid coupling needs
be decoupled for detaching the sample ejection head. Said fluid
coupling preferably comprises a corresponding valve such that
leakage of system fluid is prevented.
[0027] The pressure controller provided for controlling the system
fluid pressure generates a vacuum in the system fluid, which is
required for the intake of a test or sample fluid such that a given
quantity of test fluid is aspirated for pipetting purposes.
Subsequently, the aspirated sample fluid is ejected with the aid of
the micropumps with only a small quantity of the aspirated test
fluid being ejected by the micropumps. The quantity of aspirated
test fluid is thus fed via the micropumps to a plurality of wells
or droplet by droplet to one well each. The total quantity to be
supplied to a well can also be obtained by ejecting several
droplets into one and the same well. This offers the advantage that
the well is filled with a sufficient quantity of fluid even if a
few droplets do not reach or do not completely reach the
corresponding well. When the test fluid is almost completely
ejected into the wells, the pipettes are cleaned by moving the
pipettes over a cleaning station and washing them with the system
fluid.
[0028] In addition to the storage container containing test fluid
the sample ejection head may also include a reservoir for a
cleaning fluid. This ensures that during exchange of the
pipettes/dispensers the sample ejection device is not contaminated
by cleaning fluid. It is thus prevented that cleaning fluid flows
into the wells of the sample carrier thus falsifying the measuring
result.
[0029] The sample ejection device and the sample ejection head
according to the invention are in particular suited for use in
biological and/or chemical processes and preferably in the sector
of diagnostics and/or research in the field of pharmaceutical
products.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Hereunder a preferred embodiment of the invention is
explained in detail with reference to the drawings in which:
[0031] FIG. 1 shows a schematical view of the essential components
of a sample ejection device, and
[0032] FIG. 2 shows a perspective schematical view of a sample
ejection head according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0033] A sample ejection device comprises a sample ejection head 10
as the central component. In the embodiment shown in FIGS. 1 and 2
said sample ejection device is a pipetting device for pipetting
fluids. Below the pipettes 12 of the sample ejection head 10 a
stage 14 is arranged. The stage 14 can be shifted along a guide
rail 16 in the direction indicated by the arrow 15. Further the
stage 14 is adapted to pivot about a central axis.
[0034] On the stage 14 for example two carrier plates 17,18 are
arranged. Further the stage 14 comprises a cleaning station 20.
[0035] The sample ejection head 10 is fastened via a reception part
22 to a frame of the sample ejection device. The entire sample
ejection head 10, together with the reception part 22, can be moved
in vertical direction. Owing to the vertical movement of the sample
ejection head 10 the pipettes 12 are for example lowered into the
wells of the carrier plates 17 or 18.
[0036] During a conventional pipetting process the pipettes 12 are,
in a first step, lowered into the wells of the carrier plate 17 and
take a sample fluid from said wells. This is effected for example
by applying a vacuum to the pipettes 12. For taking in test or
sample fluid the pipettes 12 contain system fluid to which a vacuum
is applied. Then the stage 14 is shifted and pivoted such that the
pipettes 12 are arranged above the wells of the carrier plate 18.
The pipettes 12 are now lowered into the wells on the carrier plate
18 and eject, in several steps, the fluid taken from the wells of
the carrier plate 17 into a plurality of well rows. The carrier
plates 17,18 may be arranged on the stage 14 such that the stage 14
needs not be pivoted.
[0037] Then the entire sample ejection head 10, together with the
pipettes 12, is moved upward in vertical direction such that there
is a distance between the tips of the pipettes 12 and the carrier
plate 18. Now the stage 14 is shifted in the direction indicated by
the arrow 15 such that the pipettes 12 are arranged above the
cleaning station 20. In this position cleaning fluid flows through
the pipettes 12 into the drip container of the cleaning station 20.
To prevent cleaning fluid droplets from adhering to the tip of the
pipettes 12 the sample ejection head 10 is moved downward in
vertical direction until the tip of the pipettes 12 touch a dabbing
fleece or similar which absorbs the cleaning fluid.
[0038] In the next step the stage 14 is shifted such that the
pipettes 12 are again arranged above the previously filled wells of
the carrier plate 18. In the following step the sample ejection
head 10 is lowered again and test fluid is fed from the storage
containers 24 connected with the pipettes 12 to the corresponding
wells.
[0039] Thereafter the pipettes 12 are cleaned again so that a
pipetting process is completed. The pipetting illustrated above is
a typical pipetting process. However with the aid of the sample
ejection device described above other pipetting processes can be
carried out in various process steps. The idea of the invention is
that a sample ejection head 10 is provided which can be exchanged
as a whole. This aspect is independent of the pipetting process
carried out by means of the sample ejection device.
[0040] The sample ejection device further comprises a control unit
26 for controlling the sample ejection head 10. The control unit 26
controls, inter alia, the vertical movement of the sample ejection
head 10 and the valves provided in the sample ejection head 10.
Further the movement of the stage 14 can be controlled by the
control unit 26 or another control unit.
[0041] For exact determination of the position of the pipettes 12
relative to the wells of the carrier plates 17,18 the sample
ejection device further comprises a monitoring unit 28 which in the
embodiment described is a video monitoring unit. It is also
possible to provide sensors for position monitoring purposes.
[0042] The sample ejection device further comprises monitors 30.
Via the monitors 30 for example the sequence of operations of the
pipetting process can be monitored. Further the picture taken by a
camera 28 can be displayed to check whether the pipetting processes
have been carried out without any troubles.
[0043] Further the sample ejection device comprises an illumination
unit 31.
[0044] The sample ejection head 10 (FIG. 2) is provided with a
holder 32 which is of plate-type configuration in the embodiment
described. An L-shaped reception device 34 is fastened to the
holder 32. The reception device 34 supports the pipettes 12. The
pipettes 12 are connected with the L-shaped reception device 34 via
a a web 36. With the aid of screws 38 each individual pipette 12
can be adjusted relatively to the holder 32.
[0045] The holder 32 further serves for receiving the storage
containers 24. In the illustrated embodiment of the pipetting head
the storage containers 24 are filled with system fluid. If the
sample ejection head 10 is a device for dispensing fluid, the
storage container 24 is filled with a test fluid. The test fluid is
supplied via dispensers 12 to the wells. For dispensing very small
quantities of test fluid micropumps 46 are used which are arranged
in the dispensers 12. For controlling the temperature of the test
fluid the storage containers 24 are surrounded by a metal housing
connected with a cooling and/or heating unit which is not shown in
the drawings. The housing 40 comprises a slot-type viewing port 42
through which the quantity of fluid contained in the storage
containers 24 can be read. The storage containers 24 may be
provided with an optical level sensor.
[0046] For supplying the pipettes 12 with system fluid the storage
containers 24 are connected via tubes 44 with the pipettes 12.
During pipetting of sample fluid from a first titer plate 17 (FIG.
1) onto a second titer plate 18 a vacuum is applied to the system
fluid such that the pipettes 12 aspirate sample fluid from the
titer plate 17. Subsequently, the aspirated sample fluid is ejected
in several steps to a plurality of well rows of the carrier plate
18. For this purpose the micropumps 46 are activated
accordingly.
[0047] For controlling the micropumps 46 controllers 48 are
provided. The controller 48 for the micropumps 46 also form part of
the sample ejection head 10. The controller 48 for the micropumps
46 are permanently attached to the holder 32 of the sample ejection
head 10. For controlling the micropumps 46 said pumps 46 are
connected via electrical lines, which are not shown in the
drawings, with the pressure controllers 48. The controller 48 for
the micropumps 46 may be connected via further lines with the
control unit 26 (FIG. 1).
[0048] To allow for easy exchange of the sample ejection head 10
the holder 32 comprises dovetailed grooves 50. In the illustrated
embodiment said grooves 50 extend in vertical direction over the
entire rear side of the plate-type holder 32 facing the reception
part 22. Said reception part 22 is provided with corresponding
dovetailed projections or guide rails.
[0049] The reception part 22 comprises dovetailed grooves 52 on the
side facing the sample ejection device. With the aid of the
dovetailed grooves 52 the reception part 22 can be shifted in
vertical direction. By shifting the reception part 22 in vertical
direction the sample ejection head 10 attached to the reception
part 22 is also shifted in vertical direction.
[0050] For exchanging the sample ejection head 10 the head 10 needs
merely be removed from the projections in vertical direction. The
new sample ejection head 10 can then be attached in vertical
direction onto the projections of the reception part 22. The
reception part 22 comprises a stop element such that the sample
ejection head 10 is retained in a defined horizontal position.
[0051] In addition to the dovetailed groove 50 and the dovetailed
projections on the reception part 22 a quick-acting closure, for
example in the form of a clamping lever with eccentric, may be
provided. The quick-acting closure provides a permanent connection
between the holder 32 and the reception part 22. The entire sample
ejection head 10 is thus permanently attached to the reception part
22 in a simple manner.
[0052] The sample ejection head 10 shown in FIG. 2 is a double head
configuration. Each of the two heads comprises a metal housing 40
accommodating a storage container 24. Further each of the two
sample ejection heads is provided with a reception device 34 which
supports, in addition to the storage container 24, the pipettes 12
plus micropumps 46. The two sample ejection heads are connected via
bolts 54 and, if necessary, via a quick-acting closure with the
holder 32 and are easily removable from the latter.
[0053] For vertical movement of the sample ejection head 10 the
reception part 22 is moved up and down on guide rails, which are
not shown in the drawings, meshing in the grooves 52. Provision of
a reception part on the sample ejection device for receiving the
sample ejection head 10 offers the advantage that the vertical
movement of the sample ejection head 10 is effected by movement of
the reception part 22. Activation units and the connection between
the activation units and the reception part 22 thus remain on the
sample ejection device when the sample ejection head 10 is
exchanged. This facilitates exchange of the sample ejection head
10.
[0054] Although a preferred embodiment of the invention has been
specifically illustrated and described herein, it is to be
understood that minor variations may be made in the device without
departing from the spirit and scope of the invention, as defined in
the appended claims.
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